Hydrocatalytic refining of lubricating oils and catalyst therefor



HYDROCATALYTIC REFINING F LUBRICATING OILS AND CATALYST THEREFOR NoDrawing. Application May 14, 1957 Serial No. 658,958

5 Claims. (Cl. 208264) This invention relates to a process for refiningor finishtreating lubricating oils or their fractions by hydrogenationunder specific, mild conditions, in the presence of a catalystconsisting of moylbdenum oxide on an alumina support containing smallamounts of silica, whereby improvements in physical properties of theproducts are obtained without impairment of the inherent good qualitiesof the'feed. More particularly, the process is one in which, throughmild hydrogenation at temperatures no greater than about 600 F. using aparticular catalyst composition, the neutralization number of alubricating oil can be reduced substantially to zero without affectingthe natural oxidation resistance, viscosity and other properties of thefeed, and over extended periods of time with no appreciable reductionincatalyst activity.

Recent developments in the hydrogenation 'of petroleum show thathydrogenation is adaptable for converting heavier oils to gasolineandgas oil, increasing the paraffinicity of kerosenes, burning oils andlubricating oils, and converting all types of asphalts to distillatefuels. Until the last few years, commercial hydrogenation has beenrestricted to the use of highly purified hydrogen at pressures greaterthan atmospheric, temperatures below the decomposition temperature ofthe feed, and in the presence of powerful but sensitive catalysts of thetype of reduced nickel. These processes were generally applicable tosulfur-free and arsenic-free materials and accordingly related primarilyto the treatment of vegetable fats and oils. By using hydrogen aloneandemploying greatly increased pressures, both coal and petroleum oilscan be liquefied to a high degree, but because of their high contents ofsulfur and oxygen compounds, the resulting products are diflicult tocrack or further refine. With the advent of 1 catalytic desulfurization,hydrogenation and reforming processes as applied to lighter stocks andthe development of sulfur-resistanct catalysts, the art has seen manydevelopments in the field of flexible methods of treating and refiningby the use of hydrogen.

In the' application of hydrogenation as a refining,

United States Patent '0 2,921,025 Patented Jan. 12, 1960 ished oil bythe use of addends to offset deficiencies in oxidation stability,demulsibility, acid number, sludge resistance and the tendency tocorrode metal parts which are directly or indirectly a result of therefining process.

Within the vast amount of art available on hydrogenation,hydrodesulfurization, destructive hydrogenation, hydrogenolysis andrelated refining processes employing hydrogen to treat a wide variety offeed stocks, attention is generallp directed to such matters andproblems as the method of catalyst preparation or pretreatment, catalystcomposition, removal or destruction of sulfur, oxygen and nitrogencompounds, removal or destruction of asphaltic or resinous compounds,the use of promoters, obtaining fluidizable catalysts, color stabilityin the product, removal of unsaturates and maintaining catalyst life oractivity. Hydrogen processing is generally conducted at temperaturesabove 750 F., employing pressures well above 500 lbs. per square "inch,and such processes inherently remove or transform both undesirable anddesirable constituents. The art has now come to recognize thatcertain ofthenaturally-occurring sulfur, oxygen and nitrogen compounds that aredestroyed or removed during these refining operations have a decidedelfect upon the oxidation stability and sludge-forming propensities ofthe refinedlubricating oils. Although it is recognized that thestability of the lubricating oil in service, wherein it is subjected tohighly complicated oxidation atmospheres catalyzed by the presence ofmetallic surfaces, which oxidation progresses as the extent of use isprolonged, may be reduced by removing certain of the more unstablenaphthenes or aromatics or diphenyls, it is the organic sulfur compoundsthat are responsible for any remaining resistance to oxidation theoilmay have after such refining methods have been applied.

Attempts have been made to isolate the sulfur compounds naturallypresent in lubricating oil fractions, as

by the formation of mercuric chloride addition comp pounds, or byselective adsorption on fullers earth, but

. oils. Differences in the activity 'of various sulfur compounds inreacting with peroxides, which are apparently present under oxidativeconditions, is explainable on the basis of structure of the sulfurcompounds and their ability to inhibit peroxide formation. However, suchreaction products are also deleterious and contribute to sludgeformation during use. The refiner, therefore, is faced with the dilemmaof refining lubricating oils to improve their flow characteristics,while still trying to retain a sufficient concentration of naturalsulfur compounds to prevent the development of appreciableconcentrations of peroxides and consequent high oxidation rates, and atthe same time vmaintaining the content of sulfur compounds suflicientlylow so that upon oxidation poses. It is'also recognized in the art thatonly through judicious application of refining methods canthe inherentstability, color properties, or viscosity-temperature characteristics ofa lubricating oil or wax be preserved, since many refining operations,including acid treatment, hy-

the concentration of deleterious oxidation innocuous.

In accordance with the present invention, it has been discovered thatlubricating oils, their fractions, and base stocks may be refined bymild hydrogenation using a molybdenum oxide-alumina-silica catalystunder particular conditions of temperature and pressure to effect thegreatest possible reduction in neutralization number of naphthenic acidcontent without adversely affecting the viscosity, viscosity index,steam emulsion number, or causing the destruction of thenaturally-occurring, oxidatiominhibiting sulfur compounds, While at'thesame time maintaining prolonged catalyst life even though the catalystis sensitive to the presence of sulfur compounds.

V Accordingly, a first object of this invention is to provide productsis a process for refining or finishing lubricating oil fractions andlubricating oil base stocks.

Another object of this invention is to provide a superior catalystcomposition and method of its utilization for The data further show thatthe catalyst composition is a critical factor with respect to cyclelife. The results show that the combination of about 9 percentmolybdenum oxide on a support consisting of 99 percent l P thePropertiesflf lubricating stocks y mild 5 alumina and 1 percent silicais a very efiective catalyst in hydrogenation. reducing acid number whenused at temperatures in the Athird object of the invention is toprovidea catalyst range of 550600 F., and that its activity is still ata for mild hydrotreating of lubricating oils, which catalyst maximumafter 161 hours of continuous processing. A contains a minor amount ofan oxide of molybdenum similar composition, containing 9 percentmolybdenum incorporated in an alumina-silica support contain g a 10oxide on alumina alone, showed poorer acid reduction predominate amountof alumina. activity and had an active cycle life of only 7 hours.

These and other objects of the invention will become Similarly,catalysts composed of lesser amounts of apparent as the descriptionth'ere'o'f proceeds molybdenum oxide maintain high activity for acid re-In order to demonstrate the invention, a series of eX- moval for a muchlonger time when the alumina support periments were conducted in which a241 viscosity neutral contains minor amounts of silica. lubricating oilstock was treated 'to mild hydrogenation at The results of Table II showfurther the specificity of diff r nt temp r re. l s at a liq idVO'IilIhe ho rly our catalyst composition for acid removal and longcycle space velocity of 1.5, and. a hydrogeh-to-oil mol ratio life. Acomposition of 9% M00 and 3% C00 on a of 6.5to.7.5, under a pressure01500 'p.s.i.g. and-employsupport consisting of activated aluminacontaining 5% ing various molybdenum oxide'containing catalysts; Thesilica was evaluated for comparative purposes, and, at lubricatingoilstock before treatment hadthe following the same operating conditions asused for our preferred characteristics: 7 catalyst, showed pooractivity, selectivity, and catalyst API 5 gravity h 242 llfe. .Thecobalt molybdate catalyst reduced theacid 20 number of a heavy residuallube oilto only about 0.5., Refractive lndex n /D 1.4863

V and at thesame time reduced the sulfur content by an Molecular welght370 appreciable amount. The results in Table 11 show the Neutralizationnumber (1948) 3.03 Vis 3 F SUS p p 241 3 detrimental effect of th s typeof catalyst and emphas ze 8 SUS the superiority of the specific'catalystcompositions of our invention for the refining of lubricating oils.Viscosity index 76 imilarly, the use of Porocel (an activated bauxiteSulfur content, wt. percent 1.13

- containing about 84% alumina, 15% silica, and minor Steam emulsion No.145 I Boflh-l ran 6 a F 72O 930 amounts of iron) as the catalyst foracid removal showed g g again the marked superiority of our catalyst forthis par- The results of these experiments are shown in Table I. ticularpurpose. The results in Table IIobtained with Results with a catalyst ofthis invention are compared Porocel also demonstrate its short'activelife compared to results with two well-known commercial catalysts in tothe catalysts of our invention. Table II. 5

TABLE I Hydrotreating lubricating oil Catalyst Comp. Characteristics ofProduct Tenflp.

Run Base Comp. treat- Vis., SUS Wt. Steam .Vol. Catalyst Life 1 N0.Perment, M01. Neut Per- .Emul- P er- V I cent F. API Color C.R. 1WD Wt.No VI cent sion cent Lube M005 5102 Also: 100 F. 210 -F. No. ']7?1 Stockhrs. bbl./t0n

1 Length of service before Neut. N 0. reached 0.1 at which timeregeneration was necessary.

2 Neut. N0. at end of 12 hours of operation.

silica supports are eifective catalysts for the neutralization oflubncating'oil stocks and that the greatest effectiveness is obtained attemperatures of 600 F. or lower. It should 'be noted also that the,greatest eificiency in .acid neutralization is obtained over thosecatalyst compositions wherem the molybdenum oxide is incorporated intoporous plied where the mainobje'ctof the treatment is a reduction in theneutralizationnumber of the lubricating oil a pp a ning minorproportions of silica. without appreciably afiecting the sulfur contentand vis- Yields Length I of Run,

without affecting said mineral Reactor What is claimed is: 1. Theprocess of refining mineral lubricating oils, hav- Pressure, Tempp.s.i.g.

5 to weight percent of molybdenum oxide must be present and the aluminasupport must contain from between about 90 to 99.95% alumina, whichmeans that the silica content can vary between 0.05 to 10%.

ing natural resistance to oxidation and deterioration due to the contentof naturally-occurring sulfur compounds therein and containing acidiccompounds whereby said the content of manually-occurring sulfurcompounds and without deleteriously affecting the viscosity, viscosityindex and steam emulsion number of said mineral lubricating oils whichconsists in subjecting Hydrogen Reactor Rate 8.0.12] bbl.

' API TABLE II LHVSV Product Specifications Charge 011 Table III.

Hydrogenation of distillate and residual lube oil stocks Catalyst Sameas Run 12 Table I.

cobalt molybdate.

(In 6...- Poroeel. No. 4,

Vis., SUS

Run No.

Run No.

TABLE IV within the conditions set forth in Table IV content of acidiccompoundsis reduced tmdm n m mm m x m mrm e O w am um m mml m n u trmmmmmwm s mnqme .1 mt HT n c .WLWOIW Bi C at he CO6 n w s: $5 a .mm m 171507 0 25 2 w w 6 n t 810 .owm .OOZW wmmev Rn ...2....2....l raw 0 Emu-100 02 21 0000 m h m w 6.1 0mm. hu c t WS 6 e a t 50305334 25 55 a e m mm a m was EUMHLMMWMM e 0 .mwv MWH m w ma m m SP t M19 5 mmma mt mnausea? 0 2. 1 m m w A nmmflmmmm ufiumn a .rfi an m m ohvtmu pa t t S CS 09953631450555 mun nm N 5 0 mo m mm mmmmmmmm LLL 01 a 3 4 MN .0

n d S W .m.0 m w 64 63576 00 0 0 m w $y w e I 9779787 "QQWMQ LL 0. 0 Nnm g V n 2. n ma a u I m m ad w F sfiasmaasjnmnn as... 5 n E n w w euemnuwnwmnam D 000845 R m mh y.O L .0 d 2 1 1 11 M 0 0 0 0 ou d w n w n w nT m flmm m s S P W t6 T e V F 21 803 H mm A .m rnew g S s azaf "WW3 m0dw mn w W m Zmuaflfi 2 3 W 4 w sue s.m d 1 n n 1 79 9 mhfl y u n V m mom H 11. m tg flvb n. 0 81 2 d m an- M 1 6 15 6 n ur. .m r umnmunmu 24.88 6 .m m u1.S. 11 1 a o n otwoumumn a W b m dvmudmduduu w e mm aalumlmamum 6 tma .1 .1 mau a m mm W m w m a nmnmm m 1 mad 3 w hd hm a ann w wum m pTO D e e ew me mm mu m un U0 v. on m m m m mmnmdwmw w omtwbow nm mmnmm m u s r an I m w m mmuwm mn m m am a m :2" 1 N 6 wvnmmwwL anaamnmnn In general, the operating conditions used in treatinglubricating oils to obtain the desired results are as follows:

Temperature 450-600 F. LVHSV 0.5-2.0. Hydrogen/HG mol. ratio 5.0-10.

Pressure 100-500 p.s.i.g

H rate 1000-4000 s.c.f./bbl. By operating using the catalystcompositions of this invention, lubricating oil distillates, brightstocks, and residual oils can be improved with respect to their VI,color, neutralization number, demulsibility, and reduction in the carbonresidue, resins and oxygenated compounds, without imlubricating oils tocontact with hydrogen at a temperature percent alumina and about 1.0 wt.percent silica with about 9.0 wt. percent molybdenum oxide and analumina base containing about 95.0 wt. percent alumina and about 5.0 wt.percent silica with about 3.0 wt. percent molyhdenum oxide, andrecovering a hydrogenated lubricating oil characterized by having aneutralization number (1948 method) of below about 0.03, the originalcontent of naturally-occurring sulfur compounds, without impairment ofthe physical properties thereof.

2. The process in accordance with claim 1 in which said catalyst is analumina base containing about 94.2 wt. percent alumina and about 5.8 wt.percent silica with about 3.0 Wt. percent molybdenum oxide. 7

3. The process in accordance with claim 1 in which said catalyst is analumina base containing about 99.0

wt. percent alumina and about 1.0 wt. percent silica with abou 90mpe q nzmq yb n mox 4. The process in accordance with claim 1 in which saidcatalyst is an alumina base containing about 95.0

'wt. percent alumina andabout 5.0 wt. percent silica with about 3.0 wt.percent molybdenurmoxide.

5. The process in accordance with claim 1 in which the lubricating oilis a neutral oil having a viscosity at 100 F. of about 240, a viscosityat 210 F. of about 47, a steam emulsion number of about 145, aneutralization number of about 2.88, and a sulfur content of abou 1.13weight percent.

References Cited in the file ofthis patent ZUNITED ST ATES PATENTS2,437,532 Huffman Mar. 9, 1948 2,486,361 Nahin e,t a1. "Oct. 25, 19492,654,696 La Porte Oct. 6, 1953 2,706,167 Harper et al Apr. 12, 1955

1. THE PROCESS OF REFINING MINERAL LUBRICATING OILS, HAVING NATURALRESISTANCE TO OXIDATION AND DETERIORATION DUE TO THE CONTENT OFNATURALLY-OCCURRING SULFUR COMPOUNDS THEREIN AND CONTAINING ACIDICCOMPOUNDS WHEREBY SAID CONTENT OF ACIDIC COMPOUNDS IS REDUCED WITHOUTAFFECTING THE CONTENT OF NATURALLY-OCCURRING SULFUR COMPOUNDS ANDWITHOUT DELETERIOUSLY AFFECTING THE VISCOSITY, VISCOSITY INDEX AND STEAMEMULSION NUMBER OF SAID MINERAL LUBRICATING OILS WHICH CONSISTS INSUBJECTING SAID MINERAL LUBRICATING OILS TO CONTACT WITH HYDROGEN AT ATEMPERATURE OF BETWEEN ABOUT 550* AND 600*F. IN PRESENCE OF A CATALYSTSELECTED FROM THE GROUP CONSISTING OF AN ALUMINA BASE CONTAINING ABOUT94.2 WT. PERCENT ALUMINA AND ABOUT 5.8 WT. PERCENT SILICA WITH ABOUT 3.0WT. PERCENT MOLYBDENUM OXIDE, AN ALUMINA BASE CONTAINING ABOUT 99.0 WT.PERCENT ALUMINA AND ABOUT 1.0 WT. PERCENT SILICA WITH ABOUT 9.0 WT.PERCENT MOLYBDENUM OXIDE AND AN ALUMINA BASE CONTAINING ABOUT 95.0 WST.PERCENT ALUMINA AND ABOUT 5.0 WT. PERCENT SILICA WITH ABOUT 3.0 WT.PERCENT MOLYBDENUM OXIDE, AND RECOVERING A HYDROGENATED LUBRICATING OILCHARACTERIZED BY HAVING A NEUTRALIZATION NUMBER OIL CHARACTERIZED BYHAVING A NEUTRALIZATION NUMBER (1948 METHOD) OF BELOW ABOUT 0.03, THEORIGINAL CONTENT OF NATURALLY-OCCURRING SULFUR COMPOUNDS, WITHOUTIMPAIRMENT OF THE PHYSICAL PROPERTIES THEREOF.